The invention relates to a beam that is light in weight.
It is an object of the invention to provide safety beams that are light in weight and have a high energy absorption capacity.
This object is fulfilled in principle in that the two flanks of the beam have a form in cross section that follows the equation y=cos hyp (x) and the invention has been given the characteristics defined in the claims.
This form of flanks is the form of a free-hanging chain suspended at its ends only (i.e., catenary). With this form of the flanks, there will be no transverse forces on the flanks when there is a load on the beam, but all forces are in the bent plane of the flanks. The beam will therefore withstand greater forces than corresponding conventional beams before its deformation begins and the beam will also absorb more energy than corresponding beams with other flank forms.
The two flanks can meet directly, or alternatively, there can be a central part between the flanks. The flanks can suitably end in side flanges and the side flanges can be coupled together by means of a plurality of coupling elements that can be strips of sheet steel spot welded to the flanges or attached to them in any other way.
Alternatively, a coupling element in the form of a sheet steel cover can be attached to the flanges to give the beam a closed profile. A closed profile can also be achieved by the hydroforming of a closed blank. The beam can be symmetric or asymmetric and its height and width may vary along its length.
The above discussed embodiments of the present invention will be described further hereinbelow with reference to the accompanying figures.